CAPCOM
CAPCOM, or CAPsule COMmunications, refers to the astronaut or Mission Control staffer in charge of communications. The Habitat and Mission Control CAPCOMs communicate over a closed-circuit telephone system, which is the main audio link between the Habitat and MC supplemented by radio headsets as available. Buzzers are used to call a CAPCOM to the phone when their counterpart needs to contact them. In the Brahe, the CAPCOM phone is located on the Airlock side of the Interlock, while the Mission Control CAPCOM phone is located beside the CorelCam console.
Closed-Circuit Telephone Systems
A telephone junction box usually has four wires, of which the Green and Red wires carry content. If two telphones are wired in parallel with a power source, they will be able to communicate. This is the most basic CCTS setup, and was employed in the Brahe.
.--\/\/-.----.
| | |
_ | |
--- { } { }
| | |
._______|____|
Where {} represent telephone jacks.
With appropriate voltage, this system could be scaled to any number of telephones wired in parallel.
The simple addition of a single-pole single-throw switch in series with a telephone, would allow the Simulators to disable it from talking to the circuit, as such:
.--\/\/-.----.
| / /
_ | |
--- { } { }
| | |
._______|____|
Where the / are the switches.
The system currently being developed in the Hawking III employs all of the principles discussed above, but expands the system to employ two separate circuits. The first circuit is an inter-Hab circuit, and the second is a Hab-MC circuit. All phones on the same circuit will be able to talk to each other. The simulators will be able to disable each phone from either circuit individually, with the exception of the phone in Mission Control. However, to accomplish the equivalent effect, the simulators could disable all phones in the Habitat from the Hab-MC Circuit.
Each circuit has its own power supply and resistor to act as a load in case no phones are attached. The MC Phone is wired directly into the MC Circuit, whereas each Habitat phone is wired to a double-pole double-throw switch that will allow it to choose which circuit it will connect to.
.--\/\/-- \-< ^ >-/ -.--\/\/--.
| | | |
_ | | _
--- { } { } ---
| | | |
| | | |
|___________< ^ >_____|________|
Where the {} are telephone jacks, \ / are single throw switches, and <^> are double throw switches.
In the actual system, there are five telephones that duplicate the example phone that is connected to the double throw switch. Only one is shown here for clarity.
The final design, which is being implemented for the 2009-10 Mission is a modified version of the above circuit that uses only one power supply.
.--\/\/---< ^ A
| |
| { } P (Phone)
| |
.--\/\/---< ^ B
| |
_ |
--- |
|_________<< C
Apologizing for the complete unclarity of the above circuit diagram, it attempts to show that the circuit is split into two parallel systems right after the power supply with the switches wired so that they will choose between one of the two systems as opposed to one of two circuits in the earlier version of the circuit.
If the bottom of the double pole double throw switch appears as below, then each prong will be wired to the appropriately labeled wire in the above diagram.
A< >C P< >P B< >C
